In this paper we detail the design and implementation of an Eclipse plug-in that supports construction, analysis and elaboration of Modal Transition Systems. The plug-in supports construction of MTS using FSP process algebra and synthetising from scenarios and FLTL safety properties. These models could be animated and model checked. The MTSA-Eclipse plug-in is publicly available at: http://lafhis.dc.uba.ar/ suchitel/MTSA.html. Categories and Subject Descriptors 2.1 [Software Engineering]: Requirements/Specifications General Terms DESIGN Keywords Eclipse, MTS, Synthesis, FLTL, Scenarios